1. Field of the Invention
The present invention relates to a developing method and a developing apparatus each for developing an exposed pattern after a resist film formed on a substrate such as a semiconductor wafer, an LCD substrate, or the like is exposed in a predetermined pattern.
2. Description of the Related Art
In a coating and developing system for a photolithography process in processes of semiconductor device fabrication, for example, resist coating processing for forming a resist film on the front surface of a semiconductor wafer and developing processing for developing the wafer after performance of exposure processing for the resist-coated semiconductor wafer are performed.
In the developing processing, the wafer which has undergone exposure in a predetermined pattern, post-exposure bake processing and cooling processing is carried into a developing unit to be mounted on a spin chuck. A developing solution is supplied from a developing solution supply nozzle and applied (heaped up) so as to have a thickness of 1 mm, for example, on the entire surface of the semiconductor wafer, and thus a developing solution puddle is formed. The wafer stands still for a predetermined period of time with the developing solution puddle being formed, and developing processing progresses by natural convection. Thereafter, the developing solution is blown off by the semiconductor wafer being rotated by the spin chuck, and then a rinse solution is discharged from a rinse solution supply nozzle to wash away the developing solution remaining on the wafer. Subsequently, the spin chuck is rotated at a high speed, whereby the developing solution and the rinse solution remaining on the semiconductor wafer are blown away so that the wafer is dried. Thus, a series of developing processing is completed.
When the developing solution puddle is formed in this developing processing, nozzles of various shapes are used for applying the developing solution onto the entire surface of the semiconductor wafer, and the wafer is rotated and the nozzle is scan-moved while the developing solution is being discharged from the nozzle.
In the aforesaid prior developing method, however, the time to heap up the developing solution, impact at the time of supply of the developing solution, displacement speed of the developing solution, and the like are uneven in the surface of the semiconductor wafer by any means when the developing solution puddle is formed on the semiconductor wafer, thereby making it difficult to obtain uniformity of line width. Moreover, defects are prone to occur due to entrance of bubbles in heaping up the liquid and the like.
Recently, with high integration of devices from 64 megabytes to 256 megabytes, it is increasingly demanded to make circuit patterns more minute, and the minimum line width almost reaches a super-submicron region of not more than 0.2 xcexcm. In order to meet the demand, a chemically amplified resist is used as a resist capable of micromachining, but the chemically amplified resist has poor wettability for the developing solution, so that the aforesaid defects are prone to occur. When micromachining is performed with the chemically amplified resist, the ununiformity of line width due to the aforesaid unevenness becomes remarkable because of quite high sensitivity of the chemically amplified resist for the developing solution.
An object of the present invention is to provide a developing method and developing apparatus in each of which line width can be made uniform and defects do not tend to occur during coating of the developing solution.
To attain the above object, a first aspect of the present invention is a developing method for developing an exposed pattern after a resist film formed on a substrate is exposed in a predetermined pattern, comprising the steps of: adding a substance capable of decreasing fluidity of a developing solution to the developing solution; causing the developing solution to which the substance is added to become low-fluid under a predetermined condition and applying the developing solution onto the exposed resist film on the substrate; and thereafter giving a predetermined trigger to the developing solution to cause the developing solution to become high-fluid to allow developing to progress.
According to the present invention, the substance capable of decreasing fluidity of the developing solution is added to the developing solution, the developing solution to which the substance is added is caused to become low-fluid under a predetermined condition, and the developing solution is applied onto the exposed resist film on the substrate, whereby developing scarcely progresses at a point of time when the developing solution is applied. The developing solution is caused to become high-fluid after application to allow developing to progress, whereby the developing progresses on the entire substrate all at once. Consequently, time difference in the start time of developing does not occur in the surface of the substrate, thereby enabling uniform developing and improving line width uniformity (CD value uniformity) in the surface of the substrate. Further, since developing progresses all at once after the developing solution is applied and the developing solution is applied in a low-fluid state, the method to heap up the developing solution is not restricted. Furthermore, the developing solution does not directly attack the resist film, thereby decreasing defects.
A second aspect of the present invention is a developing method for developing an exposed pattern after a resist film formed on a substrate is exposed in a predetermined pattern, comprising the steps of: adding a substance changeable from a low-fluid state to a high-fluid state with an increase in temperature to a developing solution; causing the developing solution to which the substance is added to become low-fluid at a predetermined temperature and applying the developing solution onto the exposed resist film on the substrate; and thereafter increasing the temperature of the developing solution to cause the developing solution to become high-fluid to allow developing to progress.
According to the present invention, the substance changeable from a low-fluid state to a high-fluid state with an increase in temperature is added to the developing solution, the developing solution to which the substance is added is caused to become low-fluid at a predetermined temperature, and the developing solution is applied onto the exposed resist film on the substrate, whereby developing scarcely progresses at a point of time when the developing solution is applied. The developing solution is caused to become high-fluid by increasing temperature of the developing solution after application to allow developing to progress, whereby the developing progresses on the entire substrate all at once. Consequently, the same effect as the above can be obtained.
A third aspect of the present invention is a developing apparatus for developing an exposed pattern after a resist film formed on a substrate is exposed in a predetermined pattern, comprising: means for causing a developing solution to which a substance capable of decreasing fluidity of the developing solution is added to become low-fluid under a predetermined condition and applying the developing solution onto the exposed resist film on the substrate; and means for giving a predetermined trigger to the developing solution to cause the developing solution to become high-fluid to allow developing to progress.
A fourth aspect of the present invention is a developing apparatus for developing an exposed pattern after a resist film formed on a substrate is exposed in a predetermined pattern, comprising: means for applying a developing solution to which gelatin is added and which is made a first temperature onto the exposed resist film on the substrate; and means for increasing the temperature of the substrate coated with the resist film from the first temperature to a second temperature which is higher than the first temperature.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.